Photographic-imbibition dye printing process



Jan, 9, 1951 w, J, wE -rs 2,537,924

PHOTOGRAPHIC IMBIBITION DYE PRINTING PROCESS Filed Oct. 2, 1947 HCOLLOID MATRIX C'ONTA/NMG' DYE AND ARYL JULFON/C ACID WALTER J. WEIERTSIN VEN TOR 1th PM UZML/M ATTORNEYS Patented Jan. 9, 1951PHOTOGRAPHIC-IMBIBITION DYE i PRINTING PROCESS Walter J. Weyerts,Rochester, N. Y., assignor to Eastman Kodak Company, Rochester, N. Y., acorporation of New Jersey Application October 2, 1947, Serial No.777,494

9 Claims. 1

This invention relates to color photography and more particularly to aprocess in color photography of controlling the contrast of dye imagesin the imbibition dye printing process.

In the imbibition dye transfer process of color photography the methodof controlling contrast of dye images by adjustments in pH of the dyebaths with, for example, ordinary acids such as acetic acid, is wellknown. With solutions of acid dyes at relatively high pH values or theorder of 4-5, low-contrast images are obtained with transfers fromgelatin relief matrices. As the pH of the dye baths is lowered thecontrast of the transfers becomes higher until a certain pH is reachedbelow which the matrices will not take up any noticeably increasedamounts of dye. Therefore a maximum contrast is reached. A givenincrement in pH will cause increasingly greater changes in contrast asthe pH of a dye bath is raised above the value of maximum contrast. Dyesolutions above pH of about 4.0 are very sensitive to slight changes inpH, some dyes showing a noticeable effect on contrast with a change ofonly 0.1 pH unit. A similar change in pH of a dye bath at pH valuesbelow about 3.0 with most dyes has a negligible efiect on the contrastof a print. Furthermore dye baths at these lower pH values show lesseffect of dye concentration on the density of the prints. Because of theabove effects it would be advantageous to work with dye baths at low pHranges if some means could be provided for varying contrast at the lowpH values.

According to my invention contrast is controlled in imbibition dyeprinting processes, particularly at low pH ranges, by incorporating intothe dye baths certain organic acids or their soluble salts which competewith the dye when incorporated into a matrixior transfer to theimbibition dye printing blank. One advantage of my process lies in thefact that I am able to work at low pH ranges where slight changes in pHhave but little eil'ecton contrast. I am also able to obtain lowcontrast dye images when operating at low pH values. Further, operatingaccording to my invention the concentration of dye in a dye bath is notas critical as previously since dye concentration has less effect inranges of low pH. Also some dye baths are more stable when operatingwithin the low pH range.

One object of my invention isto provide a new type of dye bath suitablefor varying contrast or controlling contrast especially at low ranges ofpH. Another object of my invention is to provide a; dye bath suitablefor use at practically any (c1. nil-149.1)

is to provide the materials and describe the process of using the samein a dye imbibition print ing process. Further objects of my inventionwill become apparent by consideration of the following description of myinvention.

These objects. are accomplished by incorporating into a dye bathsuitable for use in the imbibition dye printing process a substantiallycolorless aryl sulfonic acid and treating an imbibition dye printingmatrix with this bath and printing dye images from a matrix'thus treatedin the usual manner.

My invention may be readily understood by consideration of the followingdrawings wherein Fig. 1 shows an enlarged cross-sectional view of aphotographic film carrying a matrix containing dye and an aryl sulfonicacid of the invention. The photographic element, according to Fig. 1 ofthe drawings, consists of a support Ill generally composed of a.cellulose ester film base or other suitable material such as paper or asynthetic resin film-forming material. Support In carries the matrixrelief images I I containing dye and the aryl sulfonic acid or acids ofthe invention dispersed in a colloid such as, preferably, gelatin,

albumin or a synthetic resin; for example, polyvinyl alcohol. Generally,my invention operates better using gelatin as the colloid materialbecause of its well-known response to variations in pH in the imbibitiondye printing process.

My invention will now be described with particular reference to theaccompanying drawings. I take a substantially unhardened emulsion layercoated on a support such as ll! of Fig. 1 of the drawings, and processit to a relief image by the methods well known to the art and followingthis treat the relief image with an acid dye bath the pH of which may becontrolled by the use of acetic, citric or similar acids, the bath alsocontaining a water-soluble high molecular weight aryl sulfonic acid ofthe invention, or a soluble salt thereof, such as an alkali metal salt.and then the dyed matrix is used for printing dye images in theconventional manner by superimposing the matrix onto an imbibition blanksuch as paper carrying it desirable a colloid layer such as gelatincontaining a mordant. The organic acids of the invention which are usedin the dye bath in addition to the acid such as acetic acid are,phenolphthaleine-, terephenyl-, aryl methane, napht alene-. naphthol-,naptholamine-. naphthylamine-, diphenyl-. hydroxy-diphenyl-,anthraquinone-sulfonic acids, and certain benzene sulfonic acids havinga straight chain of carbon 3 atoms or halogen atoms substituted on thebenzene ring, and the water-soluble metal salts such as the alkali metalsalts of these acids.

As examples of the acids which are suitable for use in the dye bathaccording to my invention are the following list of compounds which areby no means exhaustive of those acids or salts which are suitable. Theacids are numbered for convenience of later reference thereto.

fonate Sodium diphenyl methane p,p-disulfonateSodium-o-terephenyl-4-sulfonate Sodium-m-terephenyl-4 =-sulfonate Theacids orsalt form of the above is used depending on which is mostconvenient or from solubility which is most desirable.

Not all aryl sulfonic acids function in the optimum' manner whenincorporated into the dye bath. Some other acids, or salts of suchacids, would not ordinarily be used because of their insolubility orlimited solubility in the dye bath when Water is used as the solvent fordispersing the dye used for making the transfer to the imbibition blank.When solvents are used in the dye bath for dispersing the dye and acid,the group of'compounds suitable is enlarged. Benzene sulfonic acid ortoluene sulfonic acid are generally not very effective in varying orcontrolling the contrast at the low pH range. Similarly, when the carbonchain on the aromatic nucleus is of such length that the acid assumesthe character of wetting agents, the acid is generally not suitable foruse in my invention. With benzene sulfonic acids, generally the limit tothe number of carbon atoms in the chain is four. Similarly, when thenucleus consists of a naphthalene group the alkyl substituent should notbe so long (more than 4 carbon atoms) that the compound has thecharacter of a surface-active compound. The surface-active compounds areuseful in reducing highlight densities and in cutting back the toe ofthe characteristic curve. In the preferred embodiment of my invention Iuse aromatic sulfonic acids having a naphthalene, anthraquinone,triphenyl methane or diphenyl nucleus. The acids suitable for use in myinvention are compounds having chemical structures and imbibitionproperties similar to imbibition dyes, and when present in the dyesolutions act in competition with the dyes for transfer to theimbibition blank. The acids should be substantially colorless so as notto change the color-balance of the print, except insofar as this may bedesirable. By varying the amount of the sulfonic acid in the dyesolution or the particular dye, or the manner in which Mono-butyl phenylphenol sodium monosul- 4 the matrix is treated with the sulfonic acid orthe dye, and the pH of the dye bath, a wide range of control of contrastmay be attained.

In the following table, the examples of dyes and dye baths are given asrepresentative of the materials anddye baths suitable for use in myinvention. In the table the eflect on contrast of variation in amount ofaryl sulfonic acid given.

Table A l Sul- Aryl Sulfonic Matrix Dye pH fOIllC Acid Contrast I AcidNo. Colleen. No.

Per cent 0. 0 1. 4 1 0.1 l. 2 1 0.5 .7 l 0 1. 4 2 6 1. 2 2 1. 5 0. 6 20. 5 0. 6 2 0 1. 6 3 1. 0 1. 0 3 0 1. 2 4 25 0. 6 4 5O 0. 2 4 0 1. 2 5 1l. l 5 .4 0.6 5 0 0. 5 5 1 0. 4 5 4 0. 2 5 0 1. 2 6 1 0. 9 5 .4 0.5 5 00. 6 5 1 0. 4 5 l 0. 3 5 0. 2 i. 2 a

1 Dye A=Brllliant Alizarin Light Red B (a sulfonated benzanthrone)(concn. 0.075%

Dye B=Erio Fast Cyanine S (a sulfonated anthraquinone) (concn. 0.075%).

The characteristic curves from which the above dataare obtained weremade by'transfer of step tablet exposures from matrices Nos. 1-6 treatedwith the dye baths of composition indicated onto mordanted and hardenedgelatin-coated paper, the curves being platted as functions of log E andoptical density by reflections through a complementary colored filter.

As will be apparent to those skilled in the art, in comparing H and Dcurves a true picture is obtained only from comparison values of bothcontrast and density at definite log E values. For that reason the abovecontrast data only give indications of relative densities at log Evalues in the straightline portion of the curves whereas the actualcurves from which the data was taken showed, especially with the rinsedmatrix No. 6, appreciably less density at a given log E value when thesulfonic acids were used instead of acetic acid in the rinse bath.

The concentration of the sulfonic acid used in the dye bath variessomewhat depending on the type of dye used and the type of sulfonic acidused; that is, the effectiveness of the latter in controlling contrast,but .generally the concentration of the sulfonic acid is of the order of0.1% to 2.0% or more.

An added effect of some of the sulfonic acids of my invention, such asbenzene sulfonic acids, consist in a contrast control eifect which ismanifest by the cleaning out of the highlights in a dye print. Thiseffect is contemplated by my invention but is not generally'the effectdesired from the majority of compounds falling within the scope of myinvention. The efi'ect ordinarily obtained is that of lowering thecontrast or varying the contrast by raising or lowering the shoulder ofthe characteristiccurve of the imbibition dye print. I generally preferto incorporate the sulfonic acid into the dye bath; however, I may, in avariation of my invention, before or after dyeing the matrix, treat itwith a solution of the sulfonic acid. The table shows the compositionsof suitable baths for this purpose.

1 My invention having thus been described, it is to be understood thatthe disclosure herein is by way of example and I include in theinvention all modifications and equivalents falling within the scope ofthe appended claims.

What I claim is:

1. The process of controlling the contrast of dye images in animbibition dye printing process, which comprises incorporating into anacid imbibition dye bath containing an acid dye a watersoluble organiccompound of the group consisting of substantially colorless arylsulfonic acids having an alkyl substituent of 0 to 4 carbon atoms andwater-soluble alkali metal salts of said acids, treating an imbibitiondye printing matrix with said dye bath and transferring by imbibition adye image from said dyed matrix to an imbibition dye printing blank.

2. The process according to claim 1 wherein the organic compound is ofthe group consisting of water-soluble naphthalene sulfonic acids andwater-soluble alkali metal salts thereof.

3. The process according to claim 1 wherein the organic compound is ofthe group consisting of naphthol sulfonic acids and water-soluble alkalimetal salts thereof.

4. The process according to claim 1 wherein the organic compound is ofthe group consisting of diphenyl sulfonic acids and water-soluble alkalimetal salts thereof.

5. The process according to claim 1 wherein the organic compound is ofthe group consisting of terephenyl sulfonic acids and alkali metal saltsthereof.

6. The process according to claim 1 wherein the organic compound is4-su1fo m-terephenyl.

7. The process according to claim 1 wherein the organic compound is ofthe group consisting of anthraquinone sulfonic acid and alkali metalsalts thereof.

8. The process according to claim 1 wherein the organic compound isanthraquinone-beta sulfonic acid.

9. The process of claim 1 wherein the organic compound is of the groupconsisting of 2-naphthol-8-su1fonic acid and water-soluble alkali metalsalts thereof.

WALTER J. WEYERTS.

REFERENCES CITED The following references are of record in the NumberName Date 1,484,346 Ullmann Feb. 19, 1924 1,517,200 Donisthorpe Nov. 25,1924 1,926,556 Nusslein Sept. 12, 1933 35 2,131,146 Schlack Sept. 2'7,1938

1. THE PROCESS OF CONTROLLING THE CONTRAST OF DYE IMAGES IN ANIMBIBITION DYE PRINTING PROCESS, WHICH COMPRISES INCORPORATING INTO ANACID IMBIBITION DYE BATH CONTAINING AN ACID DYE A WATERSOLUBLE ORGANICCOMPOUND OF THE GROUP CONSISTING OF SUBSTANTIALLY COLORLESS ARYLSULFONIC ACIDS HAVING AN ALKYL SUBSTITUENT OF 0 TO 4 CARBON ATOMS